Patent GB-755211-A (GB)
Title: Improvements in or relating to adsorption treatment for thermally converted naphthas
IPC: C10G25/00
Filed: 1953-01-19
Abstract: A thermally converted petroleum naphtha, obtained by cracking, hydroforming, cyclization or other thermal conversion treatment with or without catalyst, boiling in the 200 DEG  to 450 DEG  F. range is contacted in the liquid phase with a solid porous selective adsorbent to adsorb selectively one or more components of the naphtha, and subsequently the adsorbent is contacted with a hydrocarbon solvent having a boiling range different from that of the petroleum naphtha to desorb the adsorbed components, the converted naphtha being kept out of contact with oxygen prior to and during contact with the porous selective adsorbent.  Suitable adsorbents are silica gel, activated alumina or activated carbon. It is preferred to use silica gel having a mesh size from 14-250.  Oxygen may be excluded by blanketing the naphtha with any inert gas, such as hydrogen, methane, ethane, nitrogen, helium, argon, krypton, xenon or neon.  Any oxygen dissolved in the naphtha may be removed by adding an oxidation inhibitor thereto prior to the adsorption step.  Suitable inhibitors are t-butyl catechol, phenolic bodies derived from petroleum, hydroquinone, hydroxy benzoic acids, isobutyl-p-amino phenol and p-phenylene diamines.  The hydrocarbon solvent may be an unconverted petroleum fraction, such as a pentane or hexane fraction which may also contain aromatic hydrocarbons, or a second thermally converted naphtha having a different boiling range may be contacted with the adsorbent alternately with the original naphtha, oxygen then being excluded from both feeds.  The adsorption operating may be conducted at temperatures ranging from 32 DEG  to 120 DEG  F., preferably 60 DEG  to 100 DEG  F., with contact times ranging from 15 minutes to 2 hours or more.  The adsorbent may be arranged in a bed having a length to diameter ratio in the range from 1:1 to 200:1, preferably 24:1, and in amounts providing a volume ratio of adsorbent to feed hydrocarbons ranging from 0.1:1 to 14:1.  Examples are given in which a hydroformed product containing xylenes, C9 and C10 aromatics, and C9, C10 and C11 non-aromatics is contacted with a bed of silica gel, the flow interrupted and the bed contacted with hexane containing benzene.  Operation is conducted over periods ranging from 200 to 550 cycles and the effects of blanketing with methane and inhibiting are compared with operation without excluding oxygen in terms of the recovery of benzene from the hexane fraction.ALSO:A thermally converted petroleum naphtha obtained by cracking, hydroforming, cyclization or other thermal conversion treatment with or without catalyst, boiling in the 200 DEG  to 450 DEG F. range is contacted in the liquid phase with a solid porous selective adsorbent to adsorb selectively one or more components of the naphtha, and subsequently the adsorbent is contacted with a hydrocarbon solvent having a boiling range different from that of the petroleum naphtha to desorb the adsorbed components, the converted naphtha being kept out of contact with oxygen prior to and during contact with the porous selective adsorbent.  Suitable adsorbents are silica gel, activated alumina or activated carbon. It is prefered to use silica gel having a mesh size from 14-250. Oxygen may be excluded by blanketing the naphtha with any inert gas, such as hydrogen, methane, ethane, nitrogen, helium, argon, krypton, xenon or neon.  Any oxygen dissolved in the naphtha may be removed by adding an oxidation inhibitor thereto prior to the adsorption step.  Suitable inhibitors are t-butyl, catechol, phenolic bodies derived from petroleum, hydroquinone, hydroxy benzoic acids isobutyl-p-amino phenol and p-phenylene diamines. The hydrocarbon solvent may be an unconverted petroleum fraction, such as a pentane or hexane fraction which may also contain aromatic hydrocarbons, or a second thermally converted naphtha having a different boiling range may be contacted with the adsorbent alternately with the original naphtha, oxygen then being excluded from both feeds.  Examples are given in which a hydroformed product containing xylenes, C9 and C10 aromatics, and C9, C10 and C11 non-aromatics is contacted with a bed of silica gel, the flow interrupted and the bed contacted with hexane containing benzene.